Biodiversity & Conservation

A sea spider - Pycnogonum litorale

Pycnogonum littorale

Image Paul Tranter - Pycnogonum littorale feeding on an anemone. Image width ca 4 cm.
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Distribution map

Pycnogonum litorale recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

Why do the maps differ?

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Pycnogonum litorale is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Arthropoda Arthropods, joint-legged animals, e.g. insects, crustaceans & spiders
Class Pycnogonida Sea spiders
Authority (Ström, 1762)
Recent synonyms None
Map icon Recorded Distribution in Britain and Ireland Pycnogonum littorale can be found all around the coasts of Britain and Ireland and, despite its name, has been widely recorded in the sublittoral and offshore. It is the only species of the genus to be found around Britain.
Habitat information icon Habitat information Pycnogonum littorale are found on the lower shore and sublittoral, underneath flat rocks and on seaweed and feeding on sea anemones.
Text page icon Description Pycnogonum littorale has a stout body up to 5 mm in long, although considerable variation in adult sizes may occur. The body of the female is a pale white or cream, while that of the smaller males is darker, often pale brown. The dorsal and lateral surfaces are covered with tubercles, made of a pore-like structure that is surrounded by concentric rows of irregularly positioned short spines. The conically shaped proboscis tapers abruptly and is never longer than the trunk. Pycnogonum littorale have short, legs, slightly shorter than the length of the body and terminate in strongly curved claws, however no auxiliary claws are present. Nine segmented ovigers occur only in the males of this species.
Identifying features
  • Chelifores and palps absent
  • Proboscis tapers abruptly and is never longer than the trunk
  • Short curved legs are slightly shorter than the body length
  • 9-segemented ovigerous legs arepresent only in males
  • No auxiliary claws
Additional information icon Additional information Breeding generally occurs between spring and autumn and the males and females remain clinging to each other in the mating position for up to 5 weeks. Following mating the male carries the eggs for several weeks (King, 1974).

This review can be cited as follows:

Jessica Heard 2005. Pycnogonum litorale. A sea spider. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 09/02/2010]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=4225>